This is a competitive renewal application to remain one of the cooperating study centers in the NICHD Cooperative Multicenter Neonatal Research Network. Neonatal-perinatal medicine has seen the introduction of a number of principles of management and innovative methodologies without rigorous use of the controlled observation necessary for their objective evaluation. A major problem has been the balance between assuring prompt implementation of new technologies, procedures, treatments and drugs, and adequate evaluation of their safety and efficacy. Because of the urgent demands of sick infants, care is often based upon limited knowledge of new modalities and, if the infant's condition improves, the new treatment or procedure is frequently added to the arsenal of therapies before efficacy and/or safety have been sufficiently evaluated. The NICHD Cooperative Multicenter Neonatal Research Network was established to perform some of those critical studies and to change the culture of neonatology to one of evidence-based medicine.